Microelectronic devices, such as semiconductor devices and micro-mechanical or micro-optical devices are generally manufactured on and/or in a substrate using several different types of machines. In a typical manufacturing process, one or more layers of conductive materials, typically metals, are plated onto a substrate The substrate is then generally etched and polished to remove a portion of the deposited conductive layers, to form contacts and/or conductive lines.
As micro-scale devices are increasingly manufactured at ever smaller microscopic sizes, the machines used in the manufacturing processes must also become more precise. When a metal layer plated onto a substrate, generally a highly uniform thickness over all areas of the substrate is required. Achieving a uniform plating profile or thickness requires precise control of electrical current flow in the plating chamber. This correspondingly requires that the substrate be accurately positioned and centered in the plating chamber.
In most plating machines, the substrate is held in a fixture or a rotor in a head which moves the substrate from load/unload position to process position within a plating vessel holding electrolyte. Since the plating chamber is closed when the substrate is in the process position, it is not possible to visually align the substrate, or the head holding the substrate, with the vessel. Accordingly, there is a need for techniques for aligning the head with the vessel in substrate plating chambers.